Deprecate manWithIndex

If we leave mapWithIndex then we should have “withIndex” on many other operators. Instead of this, an Observable should just be zipped with an infinite stream of numbers and the zip function provides the index.
This keeps the API surface area smaller and provides the desired behavior on all operators.

Author: benjchristensen

rxjava-core/src/main/java/rx/Observable.java

@@ -3999,6 +3999,7 @@ public <R> Observable<R> map(Func1<? super T, ? extends R> func) {
      *         transformed by the given function
      * @see <a href="https://github.com/Netflix/RxJava/wiki/Transforming-Observables#mapwithindex">RxJava Wiki: mapWithIndex()</a>
      * @see <a href="http://msdn.microsoft.com/en-us/library/hh244311.aspx">MSDN: Observable.Select</a>
+     * @deprecate just use zip with {@link Observable#range(int)}
      */
     public <R> Observable<R> mapWithIndex(Func2<? super T, Integer, ? extends R> func) {
         return create(OperationMap.mapWithIndex(this, func));